In Forge, if you Edit your Server and look at your Active Sites what does it show for your domain and directory? Typically if Forge sets up a server it sets the "default" site to just point to the Laravel Public Folder. You would need to point that directory do the root of your WP install.
UPDATE
If you are setting up a second site on a server, you would just need to insure that it's root is set to point to the root of your WP install. By default when you add a site to your Forge server it creates a directory in the home directory. For example, if you add mysite.com in Forge, it would create the following path
/users/forge/mysite.com/
And your code would go under mysite.com. However if you are following your tutorial and placing it in /var/www/html then you would simply need to edit the document room (via Forge) to point to where you want it to point to. However, for better management I would simply move your Wordpress Install to the directory forge created.